FFMan
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| posted on 10/8/20 at 09:57 AM |
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Toe in/out
So on my first test driver last night, the steering was a little odd. It sort of had the opposite of self centring, fine straight ahead but as you
turned, it wanted to pull tighter into the turn.
Unable to find any direction when i came to set it up, i gave the front 1.5mm of toe in. I then found that people recommended toe-out to get a self
centring action for IVA. It has -1.5 camber.
What is the best approach here ? I can try the toe out, i just wondered what people are running ?
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minitici
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| posted on 10/8/20 at 10:32 AM |
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How much caster are you running on your front suspension?
Lack of caster will give poor self-centring.
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FFMan
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| posted on 10/8/20 at 12:16 PM |
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quote:
Originally posted by minitici
How much caster are you running on your front suspension?
Lack of caster will give poor self-centring.
i haven't measured the castor as its not adjustable without moving the suspension mounts, and given the chassis has a good build history i was
hoping they got it right.
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JAG
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| posted on 10/8/20 at 01:47 PM |
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I had my car set up at 0 degrees prior to the test - no toe in or out.
I've since played around with toe in (stable and slow to turn) and toe out (twitchy and turns in very quickly).
...and have returned it to 0 degrees (parallel wheels).
I hope that helps 
Justin
Who is this super hero? Sarge? ...No.
Rosemary, the telephone operator? ...No.
Penry, the mild-mannered janitor? ...Could be!
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Mr Whippy
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| posted on 10/8/20 at 01:49 PM |
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So starting at the silly questions first... Have you got the wishbones on the correct side? If you look down from above is the top ball joint in front
of the bottom?
Initially for setting the wheels straight I glue a thread onto the front of the front wheel rim to the rear of the rear wheel rim and adjust till its
just touching the thread with the steering wheel straight. It's actually very accurate for zero toe.
My method of adjusting toe in was to take the car into a large car park after it rained and set it so that I could slide the car with my foot on the
floor and it would not spin out on me which probably doesn't sound very scientific at all but worked for me 
[Edited on 10/8/20 by Mr Whippy]
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adithorp
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| posted on 10/8/20 at 03:42 PM |
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Using toe to correct self centering is at best only minimally effective and at worst a bodge.
You need to address castor to sort it properly. As Whippy says check your top wishbones first; you wouldn't be the first to get them the wrong
way. After that you're stuck with moving mounts or remaking the 'bones.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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cliftyhanger
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| posted on 10/8/20 at 03:55 PM |
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And have you set the rears to parallel? If not you can get "interesting" handling.
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FFMan
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| posted on 10/8/20 at 05:23 PM |
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No such thing as a silly question. Looks like top swivel joint is forward of lower hub mount. Not sure if you can see that from the pics. Assume it
should be rear of it a tad ?
Not sure how to post pics here, so dropbox links it is:-
https://www.dropbox.com/s/6rrz0vtwioiwlro/FSusp1.jpg?dl=0
https://www.dropbox.com/s/fc33py1g8e2wcbn/FSusp2.jpg?dl=0
https://www.dropbox.com/s/esq11rppinmd3n0/FSusp3.jpg?dl=0
can you tell from the way the top wishbone stays are made wether they are mounted wrong side or not ?
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steve m
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| posted on 10/8/20 at 05:50 PM |
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On my Locost book built chassis, it states toe in of 0.01 in, so that's effectively zero, and that's what I used, zero
However the castor angle in the book says top joint is 5.3% back from the front, and I built to that tolerant
But the car never felt happy, until I made the caster more like 6.5 % and it was PERFECT, infact an ex Formula 2 driver, who gave my car am almighty
thrashing, said it was neutral, this left me disappointed for a couple of minutes, until he explained, that my cars handling had no vice between
oversteer and understeer, (im still confused 20 ish years later)
Another very important piece is tyre pressure and I eventually after many attempts, had 17 psi on all four wheels
and then we add in Camber !!!
Theres an awful lot going on at the front wheels ,
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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adithorp
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| posted on 10/8/20 at 06:09 PM |
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WE HAVE A WINNER!
Wishbones are the wrong way. Long leg should be at the front. Hard to tell from those pics but I get the impression they're on the right side
but wrong way up. Looking from the front the bush for the ball joint should kick up, not down.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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FFMan
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| posted on 10/8/20 at 06:11 PM |
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quote:
Originally posted by adithorp
WE HAVE A WINNER!
Wishbones are the wrong way. Long leg should be at the front. Hard to tell from those pics but I get the impression they're on the right side
but wrong way up. Looking from the front the bush for the ball joint should kick up, not down.
Agreed - i've studied the saturn manual and as you say, long leg at the front. Will correct that and reset it all and see how it goes.
thanks all
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FFMan
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| posted on 10/8/20 at 06:13 PM |
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quote:
Originally posted by steve m
On my Locost book built chassis, it states toe in of 0.01 in, so that's effectively zero, and that's what I used, zero
However the castor angle in the book says top joint is 5.3% back from the front, and I built to that tolerant
But the car never felt happy, until I made the caster more like 6.5 % and it was PERFECT, infact an ex Formula 2 driver, who gave my car am almighty
thrashing, said it was neutral, this left me disappointed for a couple of minutes, until he explained, that my cars handling had no vice between
oversteer and understeer, (im still confused 20 ish years later)
Another very important piece is tyre pressure and I eventually after many attempts, had 17 psi on all four wheels
and then we add in Camber !!!
Theres an awful lot going on at the front wheels ,
steve
agreed there is a lot to get wrong, or ideally right. I also run a historic single seater, and on that I trust an annual setup to a professional.
17psi is also a good pressure on a cold tyre in the single seater, so not suprised it's also good on the Haynes, it's pretty much a single
seater but with 2 seats.
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steve m
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| posted on 10/8/20 at 06:20 PM |
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Most deffo, flip the top ones over !!
That must of been a bitch to drive, as even 1% difference makes big difference, and yours is around 10% !!!
steve
Thats was probably spelt wrong, or had some grammer, that the "grammer police have to have a moan at
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FFMan
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| posted on 10/8/20 at 06:24 PM |
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quote:
Originally posted by steve m
Most deffo, flip the top ones over !!
That must of been a bitch to drive, as even 1% difference makes big difference, and yours is around 10% !!!
steve
only did low speed stuff as the brakes weren't up to much either, but yes handling was odd to say the least. It was fine dead centre but once
turning wanted to turn even more. Sort of the opposite of self centring.
Am going to bleed the brakes again, glazebust the discs and fit 1144 pads also.
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FFMan
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| posted on 10/8/20 at 07:47 PM |
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OK - so flipped the top wishbones and it looks like this now:-
https://www.dropbox.com/s/36z6k61ujh3apxb/FSusp-OK.jpg?dl=0.
Camber needs sorting, ride height and toe etc but big step in the right direction - thanks
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coyoteboy
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| posted on 11/8/20 at 11:42 AM |
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Seems like these wishbone designs need a poka yoke to save people a lot of time and frustration.
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